Effects of Four Weeks of Beta-Alanine Supplementation Combined with One Week of Creatine Loading on Physical and Cognitive Performance in Military Personnel

The purpose was to investigate the effects of a 7-day creatine (Cr) loading protocol at the end of four weeks of beta-alanine supplementation (BA) on physical performance, blood lactate, cognitive performance, and resting hormonal concentrations compared to BA alone. Twenty male military personnel (age: 21.5 +/- 1.5 yrs; height: 1.78 +/- 0.05 m; body mass: 78.5 +/- 7.0 kg; BMI: 23.7 +/- 1.64 kg/m(2)) were recruited and randomized into two groups: BA + Cr or BA + placebo (PL). Participants in each group (n = 10 per group) were supplemented with 6.4 g/day of BA for 28 days. After the third week, the BA + Cr group participants were also supplemented with Cr (0.3 g/kg/day), while the BA + PL group ingested an isocaloric placebo for 7 days. Before and after supplementation, each participant performed a battery of physical and cognitive tests and provided a venous blood sample to determine resting testosterone, cortisol, and IGF-1. Furthermore, immediately after the last physical test, blood lactate was assessed. There was a significant improvement in physical performance and mathematical processing in the BA + Cr group over time (p < 0.05), while there was no change in the BA + PL group. Vertical jump performance and testosterone were significantly higher in the BA + Cr group compared to BA + PL. These results indicate that Cr loading during the final week of BA supplementation (28 days) enhanced muscular power and appears to be superior for muscular strength and cognitive performance compared to BA supplementation alone.